The alien woolly whitefly, which threatens South Africa’s citrus industry, could soon be under control – thanks to Rhodes University entomology honours student Sarah Taylor.
The alien woolly whitefly, which threatens South Africa’s citrus industry, could soon be under control – thanks to Rhodes University entomology honours student Sarah Taylor.
The woolly whitefly, Aleurothrixus floccosus, has recently emerged in Stellenbosch, Cape Town, Pretoria, Port Elizabeth and Grahamstown.
But Taylor is excited about a discovery of natural parasitoids found on the underside of a leaf of a citrus tree in Sundays River, Eastern Cape.
A parasitoid is a kind of parasite that always kills its host. Taylor asked the general public to check the underside of their citrus tree leaves and if they found a woolly white substance, to please contact her.
She had several responses from Port Elizabeth, Port Alfred, Sundays River and Grahamstown, and received specimens for research.
The results have confirmed the presence of regulating parasitoid wasps in the Sundays River Valley. (The identity of these wasps is not yet known.
This means that these South African parasitoids might be able to control the woolly whitefly population with minimal chemical applications.
Using chemicals to kill woolly whitefly in the USA and southern Europe has been mostly unsuccessful. Their woolly covering protects larvae from chemicals, which often have a much greater effect on parasitoids than on the pests themselves.
The fly has spread to citrus plantations all over the world from its native range in Central America. It is now an established pest in the United States, Southern Europe and Africa.
Taylor is involved in a project undertaken by Rhodes Entomology with Citrus Research International (CRI). CRI programme manager Sean Moore works closely with Prof Martin Hill and Taylor herself in the Department of Zoology and Entomology.
